File photo of the destoyed Jingtai stretch of the Great Wall in northwest China's Gansu Province. [Photo: Xinhua]

LANZHOU, Sept. 7-- Police in northwest China's Gansu Province have detained two people for damaging the Great Wall, local authorities said on Monday.

In an inspection tour in mid-August, the Gansu Cultural Relics Bureau found that holes had been dug under seven towers along the Wall in Jingtai County.

Staff with the bureau informed local police, which led to the detention of the two people. Police suspect they had been digging for gold.

Damaging historical structures is a crime in China. Perpetrators face fines or prison terms of up to years.

Stretching over 69 km, the Jingtai stretch of the Great Wall was built in the Ming dynasty in 1599 and is under state protection.

Unlike eastern parts of the Great Wall in Beijing and Hebei, which were mostly constructed with stones and bricks, sections in Gansu were built with earth. After centuries of erosion from wind and sandstorms, they have become extremely fragile.

Construction of the Great Wall, which was listed as a World Heritage Site by the UNESCO in 1987, began during the reign of the first emperor of Qin Dynasty (221-206 BC) in ancient China, to keep out foreign invaders, and lasted through feudal dynasties in China.

Gansu is home to about a quarter of the Great Wall.